Belt sanding and polishing machine

ABSTRACT

A BELT STANDING AND POLISHING MACHINE HAVING A CONTACT ROLL FOR APPLYING PRESSURE TO AN ENDLESS ABRASIVE BELT FOR ROUGH SANDING A WORKPIECE. AN AIR PLATEN ASSEMBLY IS POSITIONED REARWARDLY OF THE CONTACT ROLL FOR APPLYING PRESSURE TO SAID ABRASIVE BELT TO PRODUCE A FINE FINISH ON THE WORKPIECE. A SECONDARY BELT MOVES IN A DIRECTION OF TRAVEL NORMAL TO THE DIRECTION OF MOVEMENT OF THE ABRASIVE BELT AND HAS AN ACTIVE RUN LOCATED BETWEEN SAID ABRASIVE BELT AND A GRAPHITIZED STRIP OF CLOTH BEARING AGAINST THE BOTTOM OF THE PLATEN ASSEMBLY.

March 16, 1971 R. D. RUTT ET BELT -SANDING AND POLISHING MACHINE Filed Feb. 29, 1968 FIG. I

3 SheetsSheet 1 INVENTORS PAUL W. INSKEEP, JR. RICHARD D. RUTT March 16, 1971 RUTT ET AL BELT SANDING AND POLISHING MACHINE 3 Sheets-Sheet 2 Filed Feb. 29, 1968 N O m 0. NF \1 3 L/W m Wm mm INVENTORS PAUL W. INSKEEP, JR. RICHARD D RUTT March 16, 1971 R ET AL 3,570,190

BELTSANDING AND POLISHING MACHINE Filed Feb. 29, 1968 3 Sheets-Sheet 5 I INVENTORS I PAUL W. INSKEEP, JR. FIG. 4

I 5 BY RICHARD D. RUTT United States Patent 031cc 3,570,190 BELT SANDING AND POLISHING MACHINE Richard D. Rutt, Wilson, and Paul W. Inskeep, Jr., Youngstown, N.Y., assignors to The Carborundum Company, Niagara Falls, N.Y.

Filed Feb. 29, 1968, Ser. No. 709,435 Int. Cl. 1524b 21/06 U.S. Cl. 51--141 Claims ABSTRACT OF THE DESCLOSURE A belt sanding and polishing machine having a contact roll for applying pressure to an endless abrasive belt for rough sanding a workpiece. An air platen assembly is positioned rearwardly of the contact roll for applying pressure to said abrasive belt to produce a fine finish on the workpiece. A secondary belt moves in a direction of travel normal to the direction of movement of the abrasive belt and has an active run located between said abrasive belt and a graphitized strip of cloth bearing against the bottom of the platen assembly.

This invention relates to belt sanding and polishing machines and, more particularly, to a new and improved pressure means for belt sanding and polishing machine. Although the present invention may be employed on workpieces of various materials, it is most desirably used on workpieces formed of wood or veneered wood.

In belt sanding and polishing machines of a known type, an endless abrasive belt is trained about three horizontally oriented rolls, two of which are vertically spaced, the lower one being a contact roll. The third roll is an idler roll and is spaced longitudinally away from the lower contact roll. Either the upper roll or the contact roll may be driven, as desired. The workpiece is conventionally fed by means of a conveyor in a direction perpendicular to the axis of the contact roll and is subjected to the abrasive action of the belt by means of the pressure that the contact roll applies to the belt.

Although these prior known belt sanding and polishing machines have served the purposes for which they were designed, they have not been satisfactory under all conditions of operation because only line contact occurs between the belt and the workpiece, thus effecting a thin scratch or abrasive pattern along the width of the workpiece. Moreover, the accumulation of detritus on the backup graphite strip in turn impresses the same on the back of the abrasive belt deleteriously marking the work.

The general purpose of the present invention is to overcome the above disadvantages by providing an abrasive belt contact means which produce a longer effective contact length of the belt across the width of the workpiece and which effects a smoother finish on the workpiece.

It is therefore an object of the present invention to provide a new and improved belt sanding and polishing machine.

It is another object of the present invention to provide a new and improved belt sanding and polishing machine having novel belt contact means.

It is a further object of the present invention to provide a new and improved belt sanding and polishing machine having novel belt contact means for effecting a longer contact length of the abrasive belt across the width of the workpiece.

It is still another object of the present invention to provide a new and improved belt sanding and polishing machine having novel means for removing detritus from a static graphitized strip.

It is still a further object of the present invention to provide a new and improved belt sanding and polishing 3,57%,l9fi Patented Mar. 16, 1971 machine having novel means for reducing friction between the abrasive belt and the static graphitized strip.

It is yet another object of the present invention to provide a new and improved belt sanding and polishing machine which is simple and strong in construction, eflicient in its operation, and rugged and durable in use.

These and other objects of this invention will become more apparent upon consideration of the following detailed description thereof when taken in conjunction with the following drawings, in which:

FIG. 1 is a perspective view of a belt sanding and polishing machine in which a preferred illustrative embodiment of the invention is incorporated;

FIG. 2 is a rear end view, partially broken and partially in section, of the abrasive belt contact means constructed in accordance with the principles of this invention;

FIG. 3 is a fragmentary side elevational view of the belt sanding and polishing machine of FIG. 1;

FIG. 4 is an enlarged fragmentary elevational view illustrating the adjusting mechanism for the air cushioned platen shown with the cover plates removed; and

FIG. 5 is a cross-sectional view of the air platen assembly taken along the plane of line 5-5 of FIG. 4.

Referring to the drawings and particularly to FIG. 1, it will be observed that a preferred embodiment of the invention constructed in accordance with the principles of this invention is incorporated in a belt sanding and polishing machine, generally designated 10, consisting of an upright frame 12 suitably supported on a ground surface. The terms upper, lower, rearwardly, forwardly, left-hand, right-hand and the like as hereinafter used are applied only for convenience of description and should not be taken as limiting the scope of this invention.

Frame 12 contains a grinding head, generally desig nated 14, having an upper drive roll 16 and a lower contact roll 18, each suitably journaled for rotation in bearing blocks at either end thereof. Although either roll may be driven, preferably contact roll 18 is suitably driven by an electric motor (not shown) in a manner well-known in the art. An idler roll 20 is suitably journaled for rotation on grinding head 14 and is disposed rearwardly of the contact roll 18. An endless abrasive belt 22 is trained about rolls 16, 18 and 20 for movement in an orbital path.

Frame 12 is provided with beams 24 and 26 extending outwardly from both ends thereof and disposed on both sides of the frame for supporting rollers 28 and 30 journaled for rotation in bearings 32 and 34 mounted adjacent the ends of beams 24 and 26, respectively. An endless conveyor belt 36 is trained about rollers 28 and 30 for the purpose of advancing workpieces beneath abrasive belt 22 in the direction of the arrow shown in FIG. 1. The means for driving the conveyor belt 36 may be of any conventional variety, and since many such arrangements are known in the art, no illustration or further explanation is believed necessary.

Referring to FIGS. 2, 3, 4 and 5, a pressure means or air platen assembly, generally designated 40, is adjustably mounted on grinding head 14 between contact roll 18 and idler roll 20 for urging the active run of the abrasive belt 22 against a workpiece for the purpose of producing a fine finish on the same. Air platen assembly 40 includes a suitable support plate 42 having a pair of U-shaped channel members or cover plates, 44 and 46 extending longitudinally along opposite sides of plate 42 and suitably rigidly secured thereto by any suitable means, such as screws 48 and 50, respectively. Channel members 44 and 46 have leg portions which constitute flanges 52 and 54, respectively, that underlie the side portions of plate 42 and are spaced downwardly therefrom as shown in FIG. 5.

Disposed adjacent the bottom surface of plate 42 is a resilient, inflatable air bag 56 which may have separate air cells 58 as shown in FIGS. 3 and 5. Any conventional suitable means (not shown) may be provided for supplying air at a regulated pressure to each of the cells 58.

A thin, flexible, preferably metallic sheet 60, which is supported along its sides by flanges 52 and 54 of channel members 44 and 46, respectively, extends substantially along the full length and width of support plate 42 and is spaced downwardly therefrom. Rigidly secured, as by means of any suitable adhesive to the bottom surface of flexible sheet 60, is a resilient pad 62 which extends substantially the length of sheet '60 but appreciably less than the width of such sheet so as to be disposed between the free ends of flanges 52 and 54 as shown in FIG. 5.

A corugated metallic strip 66 is disposed between the bottom surface of bag 56 and the upper surface of sheet 60 with the longitudinal axes of the corrugations extending in a direction normal to the longitudinal axis of the sheet 60, said strip extending substantially the full length and width of sheet 60. Orientation of the corrugated strip in this manner allows flexibility thereof along the length of the corrugations while providing substantial rigidity normal thereto so that uniform pressure is applied across the full width of pad 62.

A wear resistant, canvas cloth strip 70, preferably a fabric impregnated with a lubricant, such as graphite by way of example, is stretched under pad 62 to protect such pad from excessive wear. Since the means for securing the free ends of the graphitized canvas strip are identical on opposite ends of the air platen assembly, it is believed that a description of the left-hand clamping means as shown in FIG. 4 will suflice. The free end of the graphitized canvas strip is secured between two clamping blocks 72 and 74 releasably secured together by means of a screw 76. An internally threaded portion 78 is provided in clamping block 72 and is cooperatively engageable with an elongated externally threaded stud 80 journaled for rotation in a bracket 82 suitably secured to the grinding head 14. A knurled knob 84 is secured onto one end of stud 80 so that turning the knob effects tensioning of the graphitized canvas strip 70.

Means are provided for raising and lowering air platen assembly 40, such means comprising a pair of differential screw members, generally designated 90, located adjacent the opposite ends of air platen assembly 40. Since both of the screw members are identical in construction, it is believed that a description of only one, as shown in FIG. 4, will suffice. Screw member comprises a threaded portion 92 threadably engageable with a threaded bore 94 located in a bracket 96 which is suitably secured to the grinding head 14. The threaded portion 92 is provided with a knurled knob 98 at the upper end thereof and a reduced diameter threaded portion 100 at the other end thereof threadably engageable with a threaded bore 102 in plate 42. Thus, turning knobs 98 effect raising or lowering of the air platen assembly 40, as desired, and the reduced diameter threaded portions 100 provide a precise, accurate adjustment of air platen assembly 40 in the position desired.

An important feature of the present invention is the provision of a secondary endless belt 106 driven in a path normal to the direction of movement of abrasive belt 22 and having an active run disposed between said graphitized canvas strip 70 and abrasive belt 22. Belt 106 is guided for movement in an orbital path about a drive roll 108, a tracking roll 110 and a tension roll 112.

Suitably supported on frame 12 is an electric motor 114 having a power shaft 116 to which is secured a drive pulley 118. An endless belt 120 is trained about pulley 118 and a driven pulley 122 mounted on a spindle 124 for rotating the same and thereby drive roll 108.

With reference to FIG. 3, it will be seen that tracking roll 110 is suitably journaled for rotation about a shaft by suitable bearing means (not shown). Shaft 130 is carried by a bracket 132 suitably secured to grinding head 14 and is pivotally mounted about a pin 134 located in bracket 132. An adjusting screw 136 is mounted in a bracket 138 rigidly secured to grinding head 14 and is provided with a lock nut 140 for maintaining said screw 136 in a fixed position. The bottom of screw 136 engages a cavity 142 in shaft 130. Thus, by manipulating screw 136 and thereby pivoting shaft 130, tracking roll 110 can be adjusted to effect optimum tracking of belt 106.

Referring now to FIG. 2 of the drawings, it will be observed that tension roll 112 is suitably rigidly mounted on shaft 146 for rotation therewith, shaft 146 being journaled for rotation adjacent one end of an elongated arm 148, the other end of said arm being pivotally mounted about pivot pin 150 suitably secured to the grinding head 14. A roller 152 is provided on the end of arm 148 remote from pivot pin 150 and is guided for arcuate movement by means of a track member 154 suitably secured to grinding head 14. Depending from grinding head 14 is a bracket 156 which carries a fluid pressure cylinder 158 containing a piston (not shown) having a piston rod 160 engageable with arm 148. Hence, tension may be applied to or removed from belt 106 by activating cylinder 158 which in turn raises or lowers arm 148, which in turn raises or lowers tension I011 112.

In operation, with air bag 56 inflated, the air platen assembly 40 is adjusted in a vertical position by means of differential screw members 90 so that the bottom surface of resilient pad 62 is positioned at an elevation sub stantially in the same horizontal plane as the active working surface or contact roll 20. The graphitized canvas strip 70 is properly tensioned by means of threaded studs 80 and belt 106 is tensioned by actuating pressure cylinder 158 which raises arm 148 and thereby tension roll 112 until the desired tension is obtained. A motor (not shown) in energized to rotate contact roll 18 and drive abrasive belt 22 in an orbital path in the direction of the arrow shown in FIG. 1. Motor 114 is energized to rotate roll 108 by means of the pulley and belt arrangement to drive belt 106 in an orbital path in the direction of the arrow shown in FIG. 1. The direction of movement of abrasive belt 22 and belt 106 is illustrated only for convenience of description and should not be taken as limiting the scope of this invention. Proper tracking is achieved by pivoting tracking roll 110 about pivot pin 134 by means of adjusting screw 136. Workpieces may now be placed on conveyor belt 36 and advanced in a direction normal to the longitudinal axis of contact roll 18.

The upper surface of the workpieces is rough sanded to remove surface irregularities as it passes beneath the abrasive belt 22 at the contact roll 18. The workpiece is further polished as it passes under the abrasive belt 22 at the air platen assembly 40 to provide a finished product having a smooth, even surface. If desired to rough sand only, air bag 56 of air platen assembly 40 may be deflated to raise the bottom surface of resilient pad 62 above the horizontal plane of the active working surface of contact roll 18. Alternatively, if only a finishing surface on the workpiece is contemplated, air platen assembly 40 may be lowered by means of differential screws 90 to bring the bottom surface of resilient pad 62 below the horizontal plane of the active working surface contact roll 18.

As a result of this invention, an improved belt sanding and polishing machine is provided for sanding workpieces in an improved and more eflicient manner. By the provision of an air platen assembly, a finer, smoother, more even surface can be obtained on the finished product. By the provision of a secondary belt traveling in a direction normal to the abrasive belt and having an active run disposed between said abrasive belt and the graphitized canvas strip, friction between the strip and abrasive belt is minimized to materially increase the useful life of the strip and the abrasive belt. Moreover, the moving belt 106 removes grit and detritus from the strip to preclude undesirable marking of the work. An

other advantage residing in the use of the present invention is that isostatic pressure is applied to the back of the abrasive belt, thus producing a longer abrading pattern across the width of the workpiece than can be achieved by conventional contact roll sanding devices.

A preferred embodiment of this invention having been described and illustrated, it is to be realized that modifications thereof may be made without departing from the broad spirit and scope of this invention as defined in the appended claims.

We claim:

1. A sanding and polishing machine comprising: a frame; a grinding head mounted on said frame; a plu rality of rolls rotatably mounted on said grinding head; an abrasive belt carried by said rolls for movement in an orbital path; one of said rolls adapted to apply work pressure against a portion of said abrasive belt; pressure means spaced from said one of said rolls for applying Work pressure against another portion of said abrasive belt; and a secondary endless belt mounted on said grinding head for movement in an orbital path normal to the orbital path of said abrasive belt and having an active run disposed between said pressure means and said abrasive belt.

2. A sanding and polishing machine as defined in claim 1 wherein said pressure means comprises a flexible sheet having a pad attached to one side thereof; and a wear resistant strip of fabric carried by said grinding head and tensioned against the side of said pad remote from said flexible sheet.

3. A sanding and polishing machine as defined in claim 2 wherein said strip of fabric is impregnated with a lubricant.

4. A sanding and polishing machine as defined in claim 3 wherein said pressure means includes a support plate, a corrugated strip of metal supported by the other side of said flexible sheet, and an inflatable bag disposed between said support plate and said corrugated strip.

5. A sanding and polishing machine as defined in claim 4 wherein said secondary endless belt has an active run disposed between said strip of fabric and said abrasive belt.

6. A sanding and polishing machine as defined in claim 5 including a drive rolls, a tracking roll, and a tension roll carried by said grinding head for guiding said secondary endless belt in said orbital path normal to the orbital path of said abrasive belt.

7. A sanding and polishing machine as defined in claim 6 including means for vertically adjusting said pressure means.

8. A pressure means adapted to be mounted on a grinding head for urging the active run of an abrasive belt against a workpiece comprising: a flexible sheet; a pad attached to one side of said flexible sheet; a wear resistant strip of fabric carried by said grinding head and tensioned against the side of said pad remote from said flexible sheet; and a secondary endless belt mounted on said grinding head for movement in an orbital path and having an active run normal to the active run of said abrasive belt and disposed between said strip of fabric and said abrasive belt.

9. A pressure means as defined in claim 8 including a support plate; a corrugated strip of metal supported by the other side of said flexible sheet; and an inflatable bag disposed between said support plate and said corrugated strip.

10. A pressure means as defined in claim 9 including a drive roll, a tracking roll and a tension roll carried by said grinding head for guiding said secondary endless belt in said orbital path normal to the active run of said abrasive belt.

References Cited UNITED STATES PATENTS 1,493,779 5/ 1924 Humphreys 51141X 2,456,217 12/1948 Rothrock 51141X 2,624,158 1/ 1953 Hendrickson 51141 3,429,079 2/1969 Winebarger 51141 OTHELL M. SIMPSON, Primary Examiner 

